US Geological Survey researchers originally set out examining the DNA and tail tissue from snakes captured in south Florida partly in order to figure out how pythons were spreading so quickly in the Sunshine State, the Miami Herald reported.

Pythons, which can grow up to 33 feet long and weigh more than 200 pounds, have slowly spread north in Everglades National Park and west into Big Cypress Swamp since their arrival in the 1980s.

Scientists suspect the original population started when the pythons escaped people's homes where they were pets or a breeding facility in South Dade, and bred from there. Today, thousands of pythons are bred as pets in the US every year, and the USGS estimates tens of thousands live wild in the Everglades.

The vast majority of the roughly 400 snakes the USGS researchers analyzed in the study were closely related to Burmese pythons, but at least 13 had markers of Indian pythons.

The interbreeding may have resulted in "hybrid vigor," a genetic term that means the offspring takes the best traits from both species.

"Hybrid vigor can potentially lead to a better ability to adapt to environmental stressors and changes," lead author of the study and USGS geneticist Margaret Hunter said in a press release. "In an invasive population like the Burmese pythons in South Florida, this could result in a broader or more rapid distribution."

Burmese pythons are swamp-dwelling reptiles, while Indian pythons usually prefer dry, wooded ground.

The number of snakes found with markers of Indian pythons is small, but could lead to the Everglades snakes' habitats expanding to a more varied landscape.

Hunter said researchers don't know how much of the overall snake population has markers of Indian pythons.

"If the Indian pythons have a wider range, perhaps these Everglades snakes now have that capability," she told the Miami Herald.

Hunter and the other authors of the study say interbreeding probably occurred before pythons became South Floridian fixtures three decades ago.